How does this happen?

[Freezeframe]

I just got my test results back after an 11 injection load. IIt said the serum b12 was OVER. 2000. I know it’s clincally unimportant because all it means is what is in the blood but... I thought any excess would be excreted? Thoughts ?

[pvanderaa]

That’s where you want it to heal nerve damage. Are you supplementing with folic acid and a daily multivitamin to keep metabolism and energy production going?

[fbirder]

It takes some time for blood levels to drop.

When you inject B12 some of it will be eliminated by the kidneys immediately. But some will stay in the blood, bound to proteins, and some will be stored in the tissues.

The kidney works in a strange way. It filters out everything in the blood, apart from large things - like cells and protein molecules. Then it reabsorbs the things that it wants. It's a bit like doing your spring cleaning by taking everything except for the furniture outside, then bringing all the stuff you actually want back into the house.

So the kidney will only filter out the B12 that is not bound to proteins. Some of that free B12 will be reabsorbed. But that reabsorption process has a limited capacity. Any free B12 beyond that capacity will get flushed out in the urine.

That makes it difficult to determine what will happen to the blood levels of B12 after an injection. Blood levels will rise as the B12 gets from the injection site into the bloodstream. There it will bind to the proteins haptocorrin and transcobalamin. After a while there will be so much B12 in the blood that all the proteins will have have picked up a B12 molecule. Then the free B12 will start getting filtered by the urine. Some will be reabsorbed, some will be eliminated.

At the same time some B12 will be getting stored in various tissues. Nobody is quite sure what happens to the B12 stored there. But it is very likely that some of it will pass back into the blood (at a rate dependent on the concentration in the tissue and the concentration in the blood).

Some of the B12 will get passed out in the bile into the small intestine. If you have any Intrinsic Factor present then this will get reabsorbed.

So you will see an initial rise in B12 levels, followed by a rapid drop, then a very, very slow decline in levels. But the rate of these processes will vary a lot from one individual to another.

I would guess that the >2000 level represents your blood carrying the maximum it can. It's getting topped up by stuff stored in the tissues.

[Freezeframe in reply to fbirder]

Thanks for the information. Your the best !

[Freezeframe in reply to fbirder]

Just to let you know I took your advice that the 5mg of folic acid was overkill. I was able to raise my folic acid level in 2 months from 8.2 to 18.4 with 400mcg folinic acid and a high folate diet.!!! Very happy